For a long time, it is well known in the state of the art to use torsion balances to measure gravity forces. These torsion balances are disclosed, for example, in Dorobantu, R.: “Gravitionsdrehwaage,” IAPG/FESG No. 4, 1999. They comprise a horizontal balance beam, which is suspended from a torsion wire defining a rotation axis. The balance beam bears two test masses on opposite sides of the torsion wire so that the torsion balance is symmetric and the center of mass of the torsion balance is in line with the rotation axis of the torsion balance. Therefore, these conventional symmetric torsion balances compensate for the gravitational attraction g of the earth, so that differential forces can be determined using the so-called “Null measurements” (e.g. tests of the “equivalence principle” as disclosed in SMITH et al.: “Short-range tests of the equivalence principle,” Physical Review D, Volume 61, 022001, 1999). The advantage of these conventional symmetric torsion balances is their very high precision with relative accuracies down to 10−13 (cf. SMITH et al.). However, the conventional symmetric torsion balances merely allow the measurement of differential forces, whereas the measurement of absolute values of gravity forces is not possible.
Further, symmetric torsion balances with more complex mass distributions (quadrupole or octupole) are known from V. B. BRAGINSKY, V. I. PANOV: “Verification of the equivalence of inertial and gravitational mass”, JETP 34, 463 (1972). These torsion balances are commonly used for eliminating certain orders of gravitational fields.
Therefore, it is an object of the invention to provide a gravity measurement apparatus allowing the measurement of absolute values of gravity forces.
Further, it is an object of the invention to combine the high precision of the aforementioned symmetric torsion balances with the possibility to measure absolute values of gravity forces.